1. Field of Invention
The subject application relates to a multi-band antenna. More particularly, the subject application relates to a multi-band antenna for a portable communication device.
2. Description of Related Art
With various exterior designs of portable communication devices, portable communication devices having metal frames have become popular. Generally, in a design of an antenna for a portable communication device having a metal frame, the metal frame is cut into a plurality of discontinuous metal structures, so that the antenna can radiate radio frequency (RF) signals.
A conventional portable communication device utilizes a planar inverted-F antenna (PIFA) and a discontinuous metal frame to construct a multi-band antenna, such that requirements of lightness, thinness, short length, and small size of the portable communication device may be realized. However, constraints in the design of a multi-band antenna are encountered due to the spacing among an antenna main body, a system ground plane and the metal frame, increasing the difficulty of design. Moreover, this discontinuous metal structure may cause a frequency shift and radiation efficiency decline of resonant modes, thereby negatively affecting the communication quality of the portable communication device.
In view of foregoing, there is an urgent need in the related field to provide a solution.